The Effect Of Empagliflozin On Hepatic Glucose Metabolism In Db/db Mice Via AMPK

Objective:Gluconeogenesis refers to the process by which the body converts non-sugar substances into glucose.Both the liver and kidneys are involved in the process of gluconeogenesis,but the ability of the kidney to gluconeogenesis is only one-tenth that of the liver.Gluconeogenesis increase in patients with type 2 diabetes,with liver gluconeogenesis accounting for the majority.Glycogen is found in the liver,kidneys,and muscles to maintain a stable blood sugar level.Therefore,improving the levels of gluconeogenesis and glycogen synthesis in diabetic patients is of great help in maintaining blood glucose levels in diabetic patients.SGLT2 inhibitors are a very effective class of hypoglycemic agents,including Canagliflozin,Dapagliflozin,and Empagliflozin(Empa).They all reduce blood glucose by reducing the renal tubules to regain glucose.However,the effects of these drugs on liver gluconeogenesis and glycogen synthesis are less studied.In this study,db/db mice as the research object for type 2 diabetes,investigated the effects of Empa on liver gluconeogenesis and glycogen synthesis in db/db mice and their possible underlying mechanisms.Methods:db/db mice with leptin receptor mutation as research objects,administered intragastrically with Empa with 3.8 mg/kg for 8 weeks.HL7702 was used as the research object,and it was treated with 0.75 mmol/L palmitic acid(PA)and treated with 8μmol/L Empa for 24 h.The m RNA expression levels of phosphoenolpyruvate carboxykinase(PEPCK),glucose-6-phosphatase(G6Pase),changes in protein expression levels and enzyme activity were tested in mouse liver and HL7702.PAS staining was used to stain mouse liver tissues and HL7702,and the expression level of glycogen synthesis-related protein glycogen synthesis kinase 3(GSK3β)was detected.The expression of AMPK pathway related proteins were examined.Intervened PA treated HL7702 with Empa and AMPK activator(AIACR)for 24 hours,and measured the activities of the key gluconeogenesis enzymes PEPCK and G6 Pase in HL7702,as well as the amount of glucose production and evaluated the effects of AMPK signaling pathway on the expression of gluconeogenesis and glycogen synthesis related proteins.Intervened palmitic acid-induced HL7702 for 24 hours with Empa,Empa and AMPK inhibitor(Compound C),then tested the activities of PEPCK and G6 Pase,glucose production and the effect of AMPK signaling pathway on gluconeogenesis and glycogen synthesis-related protein expression.Results:Compared with db/db mice,the blood glucose levels of db/db mice treated with Empa decreased,their urine glucose levels increased,and their body weight levels also decreased.After IPGTT,they were found at various time points blood glucose level decreased.Compared with db/db mice,after treated with Empa,the m RNA levels and the protein expression levels and enzyme activities of PEPCK and G6 Pase were significantly reduced;the glycogen content of mouse liver tissue increased,and the expression level of the protein GSK3β related to glycogen synthesis increased(P <0.05).Compared with HL7702 cells induced by palmitic acid alone,the m RNA,protein expression,enzyme activity and glucose production of cells PEPCK and G6 Pase decreased significantly after 24 hours of intervention with Empa;Glycogen content increased,and the expression level of GSK3β increased.In PA treated HL7702,both AIACR and Empa can improve the expression of AMPK-mediated gluconeogenesis and glycogen synthesis pathway-related proteins.In PA treated HL7702,Compound C counteracted the therapeutic effect of Empa(P<0.05).This shows that AMPK may be a key factor in Empa in the liver.Conclusions:Empa reduce blood glucose levels and body weight levels in db/db mice.Empa inhibits gluconeogenesis in the liver of db/db mice and HL7702 cells treated by palmitic acid by activating the AMPK signaling pathway.Empa increases liver glycogen synthesis in db/db mice and HL7702 cells treated by palmitic acid by activating AMPK signaling pathway.